Negligible In Vitro Recovery of Macromolecules from Microdialysis Using 100 kDa Probes and Dextran in Perfusion Fluid.

Microdialysis is applied in neurointensive care to monitor cerebral glucose metabolism. If recoverable, macromolecules may also serve as biomarkers in brain disease and provide clues to their passage across the blood-brain barrier. Our study aimed to investigate the in vitro recovery of human micro- and macromolecules using microdialysis catheters and perfusion fluids approved for clinical use. In vitro microdialysis of a bulk solution containing physiological or supraphysiological concentrations of glucose, lactate, pyruvate, human IgG, serum albumin, and hemoglobin was performed using two different catheters and perfusion fluids. One had a membrane cut-off of 20 kDa and was used with a standard CNS perfusion fluid, and the other had a membrane cut-off of 100 kDa and was perfused with the same solution supplemented with dextran. The flow rate was 0.3 µl/min. We used both push and push-pull methods. Dialysate samples were collected at 2-h intervals for 6 h and analyzed for relative recovery of each substance. The mean relative recovery of glucose, pyruvate, and lactate was > 90% in all but two sets of experiments. In contrast, the relative recovery of human IgG, serum albumin, and hemoglobin from both bulk solutions was below the lower limit of quantification (LLOQ). Using a push-pull method, recovery of human IgG, serum albumin, and hemoglobin from a bulk solution with supraphysiological concentrations were above LLOQ but with low relative recovery (range 0.9%-1.6%). In summary, exchanging the microdialysis setup from a 20 kDa catheter with a standard perfusion fluid for a 100 kDa catheter with a perfusion solution containing dextran did not affect the relative recovery of glucose and its metabolites. However, it did not result in any useful recovery of the investigated macromolecules at physiological levels, either with or without a push-pull pump system.

Moyamoya disease in a European setting: a Danish population-based study.

BACKGROUND AND PURPOSE: The incidence of moyamoya disease (MMD) in Europe is not well known. In those affected, the risk of brain hemorrhage is considered low. The present study aimed to investigate the incidence and clinical presentation of MMD in the Danish population. METHODS: Eligible patients were identified in the Danish National Patient Register from 1994 to 2017. We collected clinical and radiological data from individual patient records from neurological, neurosurgical and paediatric units across Denmark. The diagnosis was validated according to established criteria. We also extracted basic demographic data on the cohort from the Danish Civil Registration System. RESULTS: A total of 52 patients fulfilled the diagnostic criteria for MMD. Most patients were native Danes and only 15% had an East Asian background. The ratio of female to male patients was 1.8, and the incidence had two peaks: one in childhood and another in young middle age. Until 2007, MMD was only diagnosed sporadically. From 2008 onwards, the incidence rate was 0.07 per 100 000 person-years (95% confidence interval 0.05-0.09 per 100 000 person-years). The most common mode of presentation was ischaemic stroke (33%), followed by hemorrhage (23%), headache (17%) and transient ischaemic attack (14%). CONCLUSIONS: Moyamoya disease is rare in Denmark, but is associated with a considerable risk of hemorrhage. Thus, MMD should be considered in the evaluation for ischaemic as well as hemorrhagic stroke paediatric and middle-aged Caucasians.